交流电场频率对柳树-东南景天混栽修复镉污染土壤的影响

Effect of AC electric field frequency on remediation of cadmium contaminated soil by willow-Sedum alfredii Hance mixed planting

单一植物吸收的方法修复镉(Cd)污染土壤效果欠佳,交流电场联合植物可以更好地提高土壤Cd污染的治理效率。通过优化电场频率等参数可以提高土壤Cd的移动性,促进植物吸收土壤Cd。采用土壤盆栽试验的方法,研究交流电场频率(50、300 Hz)对竹柳3号和东南景天混种条件下土壤理化性质、Cd有效性、植物生长和Cd吸收积累能力的影响。与对照(没有施加电场)相比,300 Hz电场处理的土壤pH值显著降低了0.13。电场频率的提高显著提升了土壤Cd的有效性,300 Hz频率电场处理的土壤有效态Cd质量分数显著高于对照35.00%。交流电场促进了植物生长,柳树和东南景天的株高、生物量、叶片SPAD值及根系形态指标在外加50、300 Hz交流电场时均得到提高。交流电场降低了柳树各部分和东南景天地下部Cd质量分数,其中50 Hz处理柳树叶片、枝条、树干、根系和东南景天地下部Cd质量分数较对照分别降低22.16%、29.82%(P<0.05)、1.49%、15.91%(P<0.05)、31.81%(P<0.05)。相反,电场频率的提高有利于东南景天地上部Cd质量分数增加,50、300 Hz处理东南景天地上部Cd质量分数较对照分别增加43.37%、55.18%(P<0.05)。交流电场提高了植物对土壤Cd吸收积累,但不同的电场频率对植物Cd修复效率影响不同,50、300 Hz交流电场下植物地上部分总Cd积累量较对照分别显著增加24.04%、21.24%。从这2种植物上看,50 Hz交流电场更能提高柳树Cd修复效率,300 Hz交流电场更提高能东南景天Cd修复效率。本试验装置成本较低,修复效果较好,对于电场频率增强植物修复Cd效率具有很大参考价值,有较好的应用前景。

The single plant uptake method for remediation of cadmium(Cd)contaminated soil is often low efficient,while alternating current(AC)electric field combined with plants can be better for soil Cd contamination.By optimizing parameters such as electric field frequency can improve the mobility of soil Cd,promote plant uptake of soil Cd.A soil pot experiment was conducted to study the effects of(AC)electric field frequency(50 and 300 Hz)on soil physical and chemical properties,Cd availability,plant growth and Cd absorption and accumulation under the mixed planting conditions of willow(Salix sp.)and Sedum alfredii Hance.Compared to the control treatment(without application of AC electric field),the 300 Hz frequency electric field treatment significantly reduced the soil pH value by 0.13 unit.The increase of electric field frequency significantly improved the availability of Cd in soil,and the soil available Cd concentrations of 300 Hz frequency electric field treatment was significantly higher than that of the control by 35.00%.The plant height,biomass,leaf SPAD value and root morphology parameters of willow and Sedum alfredii Hance were all improved when 50 Hz or 300 Hz AC electric field was applied.The AC fields reduced Cd concentrations in all parts of willow and in the underground part of Sedum alfredii Hance.The Cd concentrations in the willow leaves,branches,trunks,roots and underground parts of Sedum alfredii Hance treated with 50 Hz decreased by 22.16%,29.82%(P<0.05),1.49%,15.91%(P<0.05)and 31.81%(P<0.05),respectively,compared with the control.The Cd concentrations in the aboveground part of Sedum alfredii Hance increased by 43.37%and 55.18%(P<0.05)in the 50 Hz and 300 Hz treatments,respectively,compared with the control.The increase of electric field frequency improved plant uptake of soil Cd and the efficiency of soil Cd phytoremediation changed with the applied electric field frequency.The total Cd accumulation in the aboveground parts of plants under 50 Hz and 300 Hz AC fields increased significantly by 24.04%and 21.24%,respectively,compared to the control.In terms of the tested two plants,the 50 Hz AC field improved the Cd remediation efficiency of willow more than that of the 300 Hz,and the 300 Hz AC field improved the Cd remediation efficiency of Sedum alfredii Hance more more than that of the 50 Hz.The experimental setup had a low cost and high restoration efficiency,providing valuable reference for using electric field frequency to enhance phytoremediation efficiency for Cd,with promising application prospects.